This DVI switch by Delock is a manually bidirectional switch for connecting different devices with DVI port. This switch offers two different applications.
You can connect two computers with DVI port to one monitor, TV or beamer etc. with DVI input port. By using the button you can select which device should display the signal.
You can connect one computer with DVI port to two displays and select the monitor which should display the signal by using the button. (Simultaneous output to multiple screens is not possible)